Known mill drive systems often comprise a large toothed ring which is arranged in spatial proximity to the treatment process. The toothed ring, together with further gear stages and with one or more electric motors, frequently forms a drive train. The further gear stages are usually arranged in a dedicated gear case which has to be aligned exactly with a common foundation.
DE 35 34 940 A1 describes a drive device for a toothed ring of a rotary tube, the drive power of which drive device is branched in a gear case to two output pinions meshing with a toothed ring. For free movability with respect to the toothed ring for setting purposes, crowned denture clutches and spherical mountings are provided in each case for the two output pinions. In this case, an intermediate stage of the gear must have free axial movability for setting purposes. Since the two output pinions are positioned fixedly with respect to one another, the gear has to be aligned relatively accurately with a common foundation. However, the crowned denture clutches cannot compensate superposed alignment errors.
DE 39 31 116 A1 discloses a drive device for a vertical mill, in which the gear case and mill housing are firmly screwed together. Consequently axes, lying far apart from one another, of the drive pinion and toothed ring have to be positioned exactly with respect to one another. A tiltably movable mounting is provided for the drive pinion, but is not sufficient for compensating excessive constraining forces.
JP 2005052799 A describes a drive device for a vertical crusher, said drive device comprising a gear unit which can be demounted as a unit for maintenance purposes. An output-side gear stage has essentially no movability for setting purposes, in order to decouple impact loads due to the treatment process from the gear unit.
In many conventional mill drive systems, forces occurring in a treatment process are in each case introduced via a plinth into a foundation or a frame by means of a plurality of axial plain bearing elements. The foundation or the frame may for manufacturing reasons have, on a bearing surface for the housing parts, pronounced dimensional and planeness tolerances which result in considerable height differences. In order to keep lubricating gaps on the plain bearing elements within a required height tolerance range, height differences of the individual plain bearing elements have to be compensated in a complicated way by manual setting. For this purpose, the foundation or the frame usually has to be measured exactly. For height compensation, setting plates are used, for example, which are mounted individually for each plinth.